14 



BULLETIlSr 18% U. S. DEPAETMENT OF AGKICULTUBE. 



At a distance of 6 feet from the top we can change to g rounds 

 12'' on center. 



EXAMPLE 4. 



Required: Vertical and lateral pressure at the bottom of a rec- 

 tangular bin 8 feet by 14 feet by 68 feet in height, walls to be of steel 

 plates, bin to be used for storing barley weighing 40 pounds per 

 cubic foot. 



Hydraulic radius = -.^..00 = 2. 55 



Diameter of equivalent regular bin = 4X2.55 = 10.2 feet. 

 For barley in a steel bin we may select for fx' a value of 0.375 and 

 for Tc a value of 0.4, then 



4 X fc X m' = 4 X 0.4 X 0.375 = 0.60. 



„, 10.20 ,^, ^ 



0. oO 



77 68 V 



At bottom yp = r^ = 4, for which yp = 49. 08. 



7= 49. 08 X 17 = 835 pounds. 



40 

 For F=40 y=nQ of 835-668 pounds per square foot. , 



i = 0. 4 X 668 = 267 pounds per square foot. 



APPENDIX. 



Values of n', the coefficient of friction of grain on different sub- 

 stances, and of Ic, the ratio of the lateral to the vertical pressure of 

 grain, as determined by the experiments of different observers are 

 presented herewith. 



Coefficients of friction of various Tcinds of grain on bin walls. 



From Airy, Wilfred. The pressure of grain. Institution of civil engineers. Minutes of proceedings. 

 Vol. 131, p. 347-358. London, 1898. 





Weight 

 ofcubic 



foot 



loosely 



filled into 



measure. 



CoeflBcient of friction. 



Kind. 



Grain on 

 grain. 



Grain on 

 rough 

 board. 



Grain on 

 smooth 

 board. 



Grain on 

 iron. 



Grain on 

 cement. 



Wheat 



Pounds. 

 49 

 39 



28 

 44 

 46 

 50 

 49 

 41 



0.466 

 .507 

 .532 

 .521 

 .616 

 .472 

 .554 

 .456 



0.412 

 .424 

 .450 

 .344 

 .435 

 .287 

 .424 

 .407 



0.361 

 .325 

 .369 

 .308 

 .322 

 .268 

 .359 

 .308 



0.414 

 .376 

 .412 

 .374 

 .366 

 .263 

 .364 

 .339 



0.444 



Barley 



.452 



Oats 



.466 



Corn 



.423 



Beans 



.442 



Peas 



.296 



Tares 



.394 



Flaxseed 



.414 







